1. Field of the Invention
This invention relates to an interface circuit for use in connecting a linear semiconductor integrated circuit (referred to as linear IC, hereinbelow) and a digital semiconductor integrated circuit (referred to as digital IC, hereinbelow).
2. Description of the Prior Art
Conventionally, in the voltage source circuit of electronic devices for automobiles, etc., a negative voltage is generated by a converter. Voltage sources using a converter provide a large output current, but have such drawbacks that the cost becomes high and the total body is bulky. Smaller voltage source circuits, however, cannot provide a large output current. In the case where such a small voltage source circuit is used to supply a negative voltage to a linear IC, and when a DTL (diode-transistor logic) or a TTL (transistor-transistor logic) is connected to the output of said linear IC, the load current for said voltage source circuit becomes large and the negative voltage rises (i.e., the absolute value of the negative voltage decreases) to affect the operation of the linear IC.